In an effort to better understand the sources of possible racial/ethnic and SES differences in physician–patient communication about cancer screening, we used baseline data from two community trials that matched multiple patients with their physicians to empirically disentangle differences between physicians from differences within physicians. For all three types of cancer screening (FOBT, mammogram and PSA), our results showed a strong education gradient in the discussion of these screening strategies where patients of lower education were less likely to have discussed the screening with their physicians. Differences in discussion rates were especially marked between the lowest educated group (less than high school) and college graduates. Our results further suggested that this difference mainly arose between patients treated by the same physicians (“within-physician” differences). Differences by the other dimension of SES, i.e., income, were less consistent across the different types of cancer screening. However, most of the significant differences by income seemed to have arisen because low-income patients are treated by different physicians than patients of higher income (“between-physician” differences).
Our findings for different dimensions of SES are noteworthy. The fact that differences by income are mainly “between-physician” differences indicates that physicians who disproportionately treat more low-income patients are likely to have a lower rate of cancer screening discussion in their practice. This pattern could have developed because of the disparities in physician training regarding physician–patient communication, disparities in the institutional support for quality improvement and consistent performance of preventive care, and/or differences in demand for these services by patient income. Physicians treating a large number of low-income patients may develop practice styles that are characterized by low rate of cancer screening discussion as a result of these and other factors.3
Our findings regarding disparities by income were consistent with the notion that physicians are not evenly distributed across communities with different levels of income and that, in seeking health care, geographic accessibility of providers is an important factor for low-income patients. In fact, our data show that low income patients in the CMC studies were treated by a disproportionately small group of physicians: 80 percent of the patients with annual household income less than 15k were seen by 60 percent of the study physicians.
By contrast, the education gradient in cancer screening discussion that we found mainly existed within physicians, indicating that education plays an important role in determining what happens during clinical encounters. At least three possible mechanisms are at play. First, patients with low education may have had less exposure to various health topics including cancer screening from sources other than one's health care providers and are thus less likely to initiate discussion with their physicians about cancer screening. In 2000, 56 percent of those with less than high school education were not aware that they needed colorectal cancer screening compared with 48 percent among high school graduates and 42 percent among those who achieved beyond high school (Finney Rutten, Nelson, and Meissner 2004
). Studies have found that patients who asked for help with smoking cessation were much more likely to have received cessation treatment (Quinn et al. 2005
). Likewise, patients who do not bring up the topic of cancer screening, all else being equal, may be less likely to receive any discussion about cancer screening from their physicians.
Second, deficits in comprehension and cognitive abilities and in health literacy in particular associated with lower education may have put these patients at a disadvantage when it comes to cancer screening (IOM 2004
). The decision about cancer screening necessarily involves tradeoffs between future benefits and current costs, which is likely an important element of physician–patient discussion. The fact that making such tradeoffs is more demanding for low-education patients makes it less likely that they engage in active discussion with their physicians.
Third, physicians may hold stereotypes of low-education patients (e.g., “low-education patients are less interested in screening”), and interact with their low-education patients in a different way, forgoing opportunities of discussing cancer screening during a clinical encounter.
Two findings stood out in our adjusted results regarding racial/ethnic differences in the discussion of cancer screening: (1) the Asian/white disparity in the discussion of FOBT and PSA, and (2) the higher rate of discussion about mammogram among black female patients compared with white females. The first finding suggests that although Asian patients may not select to see a small group of providers who practice differently (this is especially true for Asian patients in our sample since patients had to speak either English or Spanish to be eligible for the study), the cultural distance between physicians and their older Asian patients may have led to the low rate of discussion of FOBT, a type of cancer screening that has not been mass-promoted as mammogram. The black/white difference in the discussion of mammogram is in contrast with the pattern of racial/ethnic disparities normally seen in health care. In discussing more with black female patients, physicians may have applied the law of conditional probabilities when faced with greater uncertainties in communicating with minority patients (Balsa and McGuire 2001
). Although black women have a lower incidence rate of breast cancer compared with whites, their breast cancer-related mortality rate is much higher (Jemal et al. 2004
). This is consistent with the finding that black women were less likely to be diagnosed with early stage breast cancer (Schwartz et al. 2003
). In deciding whom to discuss mammogram with, physicians may have been mindful of the relatively lower screening rate among black women and delivered more discussion to their black patients. It is not clear why we do not see a similar pattern for the discussion of PSA test, given that both incidence and mortality rates are much higher among black males than white males.4
At the same time, because of the small numbers of Asian and black patients in our sample (4–8 percent of the samples), these results should be interpreted with caution.
The language variable—whether the patient was interviewed in Spanish or English—was not a significant predictor for any of these outcomes. This finding suggests that having limited English proficiency was not a substantial barrier in cancer screening discussion or patients minimized the impact of potential language barriers by choosing to see a physician who speaks the same language.
Our study has a few limitations. First of all, our physician and patient populations are from Southern California only and physicians affiliated with large groups (but not Kaiser) were not well represented in the study. As a result, our findings may not be generalizable to other geographical areas of the country or physicians practicing with large groups. Second, our outcomes of interest—discussion of cancer screening between the patient and his/her primary care physician—are self-reported by the patients and may not reflect what happened in a clinical encounter. However, previous studies found that patient self-reports of instrumental and affect aspects of clinical communication have substantial correlations with rated outcomes of audio and video records of the visits (DiMatteo et al. 2003
). Another concern is that patient self-report may be subject to recall bias, although such bias may be mitigated by the fact that we chose to study whether they ever discussed a particular cancer screening rather than their discussion within a specified recall period. There might also be concern that certain SES or racial/ethnic groups tend to over or under report their discussion. However, it is not possible to predict how differential recall between patient groups may bias our results regarding between- versus within-physician differences.
Our results suggest that disparities in health care along the different dimensions of patient SES may have arisen because of very different mechanisms and therefore may entail different remedies. In particular, we found income disparities in cancer screening discussion mainly a result of differences between physicians who treat low-income patients and those who treat patients of higher income. Disparities by patient education, on the other hand, have developed largely because the results of clinical encounters with the same physicians differ for low-education patients compared with high-education patients.
One general implication of our findings is that socioeconomic disparities in cancer screening discussion, and possibly in other areas of health care communication as well, develop because of a multitude of factors. Therefore, no magic bullet exists and a multifactorial approach is more plausible to effectively address these disparities. For example, one important practical implication based on our findings is that physicians need to be aware of the educational disparities in the receipt of cancer screening discussion and possibly also in other areas of medical care. Increased awareness may then translate into special efforts when they interact with low-education patients. On the patients' side, informational materials on cancer screening and other health education topics need to be designed in a way that they either target patients of low health literacy or they are tailored to the needs of these patients. Community health initiatives that focus on enhancing the awareness and understanding of cancer screening among low-education population and on more effective communication with one's physician during a clinical encounter may also be promising. Also in light of our findings, quality improvement efforts targeted at physicians practicing in low-income communities may be most effective in addressing disparities in cancer screening discussion and possibly other areas of preventive care by patient income.